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Fixes [YOCTO #11630] The "Yocto Project Source Repositories" section is purely conceptual and thus does not belong in the reconstituted dev-manual, which is converting to a "how-to" manual. I have moved this section to the ref-manual under "The Yocto Project Development Environment" section. Moving the section affected several things. Three figures that where in the dev-manual were copied and moved to the figures folder of the ref-manual. This required deleting them from the dev-manual and adding them to the ref-manual. The makefile had to be edited to move those figures into the ref-manual and delete them from the latest version of the dev-manual in order for the tarball of files to be correct when the manuals are made. Links to anchors within the moved section had to be fixed in various manuals. Links to the main section "id" had to be fixed to point to the ref-manual manual. (From yocto-docs rev: c619ae2bbc6be93cb0324ca44e936eefec12b28c) Signed-off-by: Scott Rifenbark <srifenbark@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
1391 lines
73 KiB
XML
1391 lines
73 KiB
XML
<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
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[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
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<chapter id='dev-manual-newbie'>
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<title>The Yocto Project Open Source Development Environment</title>
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<section id="usingpoky-changes-collaborate">
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<title>Using the Yocto Project in a Team Environment</title>
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<para>
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It might not be immediately clear how you can use the Yocto
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Project in a team environment, or scale it for a large team of
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developers.
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One of the strengths of the Yocto Project is that it is extremely
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flexible.
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Thus, you can adapt it to many different use cases and scenarios.
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However, these characteristics can cause a struggle if you are trying
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to create a working setup that scales across a large team.
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</para>
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<para>
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To help with these types of situations, this section presents
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some of the project's most successful experiences,
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practices, solutions, and available technologies that work well.
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Keep in mind, the information here is a starting point.
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You can build off it and customize it to fit any
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particular working environment and set of practices.
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</para>
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<section id='best-practices-system-configurations'>
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<title>System Configurations</title>
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<para>
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Systems across a large team should meet the needs of
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two types of developers: those working on the contents of the
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operating system image itself and those developing applications.
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Regardless of the type of developer, their workstations must
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be both reasonably powerful and run Linux.
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</para>
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<section id='best-practices-application-development'>
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<title>Application Development</title>
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<para>
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For developers who mainly do application level work
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on top of an existing software stack,
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the following list shows practices that work best.
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For information on using a Software Development Kit (SDK), see
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the
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<ulink url='&YOCTO_DOCS_SDK_URL;#sdk-intro'>Yocto Project Software Development Kit (SDK) Developer's Guide</ulink>:
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<itemizedlist>
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<listitem><para>Use a pre-built toolchain that
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contains the software stack itself.
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Then, develop the application code on top of the
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stack.
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This method works well for small numbers of relatively
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isolated applications.</para></listitem>
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<listitem><para>When possible, use the Yocto Project
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plug-in for the <trademark class='trade'>Eclipse</trademark> IDE
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and SDK development practices.
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For more information, see the
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"<ulink url='&YOCTO_DOCS_SDK_URL;'>Yocto Project Software Development Kit (SDK) Developer's Guide</ulink>".
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</para></listitem>
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<listitem><para>Keep your cross-development toolchains
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updated.
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You can do this through provisioning either as new
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toolchain downloads or as updates through a package
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update mechanism using <filename>opkg</filename>
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to provide updates to an existing toolchain.
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The exact mechanics of how and when to do this are a
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question for local policy.</para></listitem>
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<listitem><para>Use multiple toolchains installed locally
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into different locations to allow development across
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versions.</para></listitem>
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</itemizedlist>
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</para>
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</section>
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<section id='best-practices-core-system-development'>
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<title>Core System Development</title>
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<para>
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For core system development, it is often best to have the
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build system itself available on the developer workstations
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so developers can run their own builds and directly
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rebuild the software stack.
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You should keep the core system unchanged as much as
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possible and do your work in layers on top of the core system.
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Doing so gives you a greater level of portability when
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upgrading to new versions of the core system or Board
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Support Packages (BSPs).
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You can share layers amongst the developers of a particular
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project and contain the policy configuration that defines
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the project.
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</para>
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<para>
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Aside from the previous best practices, there exists a number
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of tips and tricks that can help speed up core development
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projects:
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<itemizedlist>
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<listitem><para>Use a
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<ulink url='&YOCTO_DOCS_REF_URL;#shared-state-cache'>Shared State Cache</ulink>
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(sstate) among groups of developers who are on a
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fast network.
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The best way to share sstate is through a
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Network File System (NFS) share.
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The first user to build a given component for the
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first time contributes that object to the sstate,
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while subsequent builds from other developers then
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reuse the object rather than rebuild it themselves.
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</para>
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<para>Although it is possible to use other protocols for the
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sstate such as HTTP and FTP, you should avoid these.
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Using HTTP limits the sstate to read-only and
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FTP provides poor performance.
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</para></listitem>
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<listitem><para>Have autobuilders contribute to the sstate
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pool similarly to how the developer workstations
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contribute.
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For information, see the
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"<link linkend='best-practices-autobuilders'>Autobuilders</link>"
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section.</para></listitem>
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<listitem><para>Build stand-alone tarballs that contain
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"missing" system requirements if for some reason
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developer workstations do not meet minimum system
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requirements such as latest Python versions,
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<filename>chrpath</filename>, or other tools.
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You can install and relocate the tarball exactly as you
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would the usual cross-development toolchain so that
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all developers can meet minimum version requirements
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on most distributions.</para></listitem>
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<listitem><para>Use a small number of shared,
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high performance systems for testing purposes
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(e.g. dual, six-core Xeons with 24 Gbytes of RAM
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and plenty of disk space).
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Developers can use these systems for wider, more
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extensive testing while they continue to develop
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locally using their primary development system.
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</para></listitem>
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<listitem><para>Enable the PR Service when package feeds
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need to be incremental with continually increasing
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<ulink url='&YOCTO_DOCS_REF_URL;#var-PR'>PR</ulink>
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values.
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Typically, this situation occurs when you use or
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publish package feeds and use a shared state.
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You should enable the PR Service for all users who
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use the shared state pool.
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For more information on the PR Service, see the
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"<link linkend='working-with-a-pr-service'>Working With a PR Service</link>".
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</para></listitem>
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</itemizedlist>
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</para>
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</section>
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</section>
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<section id='best-practices-source-control-management'>
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<title>Source Control Management (SCM)</title>
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<para>
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Keeping your
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<ulink url='&YOCTO_DOCS_REF_URL;#metadata'>Metadata</ulink>
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and any software you are developing under the
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control of an SCM system that is compatible
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with the OpenEmbedded build system is advisable.
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Of the SCMs BitBake supports, the
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Yocto Project team strongly recommends using
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<link linkend='git'>Git</link>.
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Git is a distributed system that is easy to backup,
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allows you to work remotely, and then connects back to the
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infrastructure.
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<note>
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For information about BitBake, see the
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<ulink url='&YOCTO_DOCS_BB_URL;'>BitBake User Manual</ulink>.
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</note>
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</para>
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<para>
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It is relatively easy to set up Git services and create
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infrastructure like
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<ulink url='&YOCTO_GIT_URL;'>http://git.yoctoproject.org</ulink>,
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which is based on server software called
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<filename>gitolite</filename> with <filename>cgit</filename>
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being used to generate the web interface that lets you view the
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repositories.
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The <filename>gitolite</filename> software identifies users
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using SSH keys and allows branch-based
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access controls to repositories that you can control as little
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or as much as necessary.
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</para>
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<note>
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The setup of these services is beyond the scope of this manual.
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However, sites such as these exist that describe how to perform
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setup:
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<itemizedlist>
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<listitem><para><ulink url='http://git-scm.com/book/ch4-8.html'>Git documentation</ulink>:
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Describes how to install <filename>gitolite</filename>
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on the server.</para></listitem>
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<listitem><para><ulink url='http://sitaramc.github.com/gitolite/master-toc.html'>The <filename>gitolite</filename> master index</ulink>:
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All topics for <filename>gitolite</filename>.
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</para></listitem>
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<listitem><para><ulink url='https://git.wiki.kernel.org/index.php/Interfaces,_frontends,_and_tools'>Interfaces, frontends, and tools</ulink>:
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Documentation on how to create interfaces and frontends
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for Git.</para></listitem>
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</itemizedlist>
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</note>
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</section>
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<section id='best-practices-autobuilders'>
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<title>Autobuilders</title>
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<para>
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Autobuilders are often the core of a development project.
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It is here that changes from individual developers are brought
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together and centrally tested and subsequent decisions about
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releases can be made.
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Autobuilders also allow for "continuous integration" style
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testing of software components and regression identification
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and tracking.
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</para>
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<para>
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See "<ulink url='http://autobuilder.yoctoproject.org'>Yocto Project Autobuilder</ulink>"
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for more information and links to buildbot.
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The Yocto Project team has found this implementation
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works well in this role.
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A public example of this is the Yocto Project
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Autobuilders, which we use to test the overall health of the
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project.
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</para>
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<para>
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The features of this system are:
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<itemizedlist>
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<listitem><para>Highlights when commits break the build.
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</para></listitem>
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<listitem><para>Populates an sstate cache from which
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developers can pull rather than requiring local
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builds.</para></listitem>
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<listitem><para>Allows commit hook triggers,
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which trigger builds when commits are made.
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</para></listitem>
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<listitem><para>Allows triggering of automated image booting
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and testing under the QuickEMUlator (QEMU).
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</para></listitem>
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<listitem><para>Supports incremental build testing and
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from-scratch builds.</para></listitem>
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<listitem><para>Shares output that allows developer
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testing and historical regression investigation.
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</para></listitem>
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<listitem><para>Creates output that can be used for releases.
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</para></listitem>
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<listitem><para>Allows scheduling of builds so that resources
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can be used efficiently.</para></listitem>
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</itemizedlist>
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</para>
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</section>
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<section id='best-practices-policies-and-change-flow'>
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<title>Policies and Change Flow</title>
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<para>
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The Yocto Project itself uses a hierarchical structure and a
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pull model.
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Scripts exist to create and send pull requests
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(i.e. <filename>create-pull-request</filename> and
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<filename>send-pull-request</filename>).
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This model is in line with other open source projects where
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maintainers are responsible for specific areas of the project
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and a single maintainer handles the final "top-of-tree" merges.
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</para>
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<note>
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You can also use a more collective push model.
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The <filename>gitolite</filename> software supports both the
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push and pull models quite easily.
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</note>
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<para>
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As with any development environment, it is important
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to document the policy used as well as any main project
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guidelines so they are understood by everyone.
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It is also a good idea to have well structured
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commit messages, which are usually a part of a project's
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guidelines.
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Good commit messages are essential when looking back in time and
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trying to understand why changes were made.
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</para>
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<para>
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If you discover that changes are needed to the core layer of the
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project, it is worth sharing those with the community as soon
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as possible.
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Chances are if you have discovered the need for changes, someone
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else in the community needs them also.
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</para>
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</section>
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<section id='best-practices-summary'>
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<title>Summary</title>
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<para>
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This section summarizes the key recommendations described in the
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previous sections:
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<itemizedlist>
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<listitem><para>Use <link linkend='git'>Git</link>
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as the source control system.</para></listitem>
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<listitem><para>Maintain your Metadata in layers that make sense
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for your situation.
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See the "<link linkend='understanding-and-creating-layers'>Understanding
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and Creating Layers</link>" section for more information on
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layers.</para></listitem>
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<listitem><para>
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Separate the project's Metadata and code by using
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separate Git repositories.
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See the
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"<ulink url='&YOCTO_DOC_REF_URL;#yocto-project-repositories'>Yocto Project Source Repositories</ulink>"
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section for information on these repositories.
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See the
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"<link linkend='getting-setup'>Getting Set Up</link>"
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section for information on how to set up local Git
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repositories for related upstream Yocto Project
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Git repositories.
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</para></listitem>
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<listitem><para>Set up the directory for the shared state cache
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(<ulink url='&YOCTO_DOCS_REF_URL;#var-SSTATE_DIR'><filename>SSTATE_DIR</filename></ulink>)
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where it makes sense.
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For example, set up the sstate cache on a system used
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by developers in the same organization and share the
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same source directories on their machines.
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</para></listitem>
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<listitem><para>Set up an Autobuilder and have it populate the
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sstate cache and source directories.</para></listitem>
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<listitem><para>The Yocto Project community encourages you
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to send patches to the project to fix bugs or add features.
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If you do submit patches, follow the project commit
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guidelines for writing good commit messages.
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See the "<link linkend='how-to-submit-a-change'>How to Submit a Change</link>"
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section.</para></listitem>
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<listitem><para>Send changes to the core sooner than later
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as others are likely to run into the same issues.
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For some guidance on mailing lists to use, see the list in the
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"<link linkend='how-to-submit-a-change'>How to Submit a Change</link>"
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section.
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For a description of the available mailing lists, see the
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||
"<ulink url='&YOCTO_DOCS_REF_URL;#resources-mailinglist'>Mailing Lists</ulink>"
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section in the Yocto Project Reference Manual.
|
||
</para></listitem>
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||
</itemizedlist>
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||
</para>
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||
</section>
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</section>
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||
|
||
<section id='licensing'>
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<title>Licensing</title>
|
||
|
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<para>
|
||
Because open source projects are open to the public, they have different licensing structures in place.
|
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License evolution for both Open Source and Free Software has an interesting history.
|
||
If you are interested in this history, you can find basic information here:
|
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<itemizedlist>
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<listitem><para><ulink url='http://en.wikipedia.org/wiki/Open-source_license'>Open source license history</ulink>
|
||
</para></listitem>
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||
<listitem><para><ulink url='http://en.wikipedia.org/wiki/Free_software_license'>Free software license
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||
history</ulink></para></listitem>
|
||
</itemizedlist>
|
||
</para>
|
||
|
||
<para>
|
||
In general, the Yocto Project is broadly licensed under the Massachusetts Institute of Technology
|
||
(MIT) License.
|
||
MIT licensing permits the reuse of software within proprietary software as long as the
|
||
license is distributed with that software.
|
||
MIT is also compatible with the GNU General Public License (GPL).
|
||
Patches to the Yocto Project follow the upstream licensing scheme.
|
||
You can find information on the MIT license
|
||
<ulink url='http://www.opensource.org/licenses/mit-license.php'>here</ulink>.
|
||
You can find information on the GNU GPL <ulink url='http://www.opensource.org/licenses/LGPL-3.0'>
|
||
here</ulink>.
|
||
</para>
|
||
|
||
<para>
|
||
When you build an image using the Yocto Project, the build process uses a
|
||
known list of licenses to ensure compliance.
|
||
You can find this list in the
|
||
<ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink> at
|
||
<filename>meta/files/common-licenses</filename>.
|
||
Once the build completes, the list of all licenses found and used during that build are
|
||
kept in the
|
||
<ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
|
||
at <filename>tmp/deploy/licenses</filename>.
|
||
</para>
|
||
|
||
<para>
|
||
If a module requires a license that is not in the base list, the build process
|
||
generates a warning during the build.
|
||
These tools make it easier for a developer to be certain of the licenses with which
|
||
their shipped products must comply.
|
||
However, even with these tools it is still up to the developer to resolve potential licensing issues.
|
||
</para>
|
||
|
||
<para>
|
||
The base list of licenses used by the build process is a combination of the Software Package
|
||
Data Exchange (SPDX) list and the Open Source Initiative (OSI) projects.
|
||
<ulink url='http://spdx.org'>SPDX Group</ulink> is a working group of the Linux Foundation
|
||
that maintains a specification
|
||
for a standard format for communicating the components, licenses, and copyrights
|
||
associated with a software package.
|
||
<ulink url='http://opensource.org'>OSI</ulink> is a corporation dedicated to the Open Source
|
||
Definition and the effort for reviewing and approving licenses that
|
||
conform to the Open Source Definition (OSD).
|
||
</para>
|
||
|
||
<para>
|
||
You can find a list of the combined SPDX and OSI licenses that the
|
||
Yocto Project uses in the
|
||
<filename>meta/files/common-licenses</filename> directory in your
|
||
<ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
|
||
</para>
|
||
|
||
<para>
|
||
For information that can help you maintain compliance with various
|
||
open source licensing during the lifecycle of a product created using
|
||
the Yocto Project, see the
|
||
"<link linkend='maintaining-open-source-license-compliance-during-your-products-lifecycle'>Maintaining Open Source License Compliance During Your Product's Lifecycle</link>"
|
||
section.
|
||
</para>
|
||
</section>
|
||
|
||
<section id='git'>
|
||
<title>Git</title>
|
||
|
||
<para>
|
||
The Yocto Project makes extensive use of Git,
|
||
which is a free, open source distributed version control system.
|
||
Git supports distributed development, non-linear development, and can handle large projects.
|
||
It is best that you have some fundamental understanding of how Git tracks projects and
|
||
how to work with Git if you are going to use the Yocto Project for development.
|
||
This section provides a quick overview of how Git works and provides you with a summary
|
||
of some essential Git commands.
|
||
</para>
|
||
|
||
<para>
|
||
For more information on Git, see
|
||
<ulink url='http://git-scm.com/documentation'></ulink>.
|
||
If you need to download Git, go to <ulink url='http://git-scm.com/download'></ulink>.
|
||
</para>
|
||
|
||
<section id='repositories-tags-and-branches'>
|
||
<title>Repositories, Tags, and Branches</title>
|
||
|
||
<para>
|
||
As mentioned earlier in the section
|
||
"<ulink url='&YOCTO_DOCS_REF_URL;#yocto-project-repositories'>Yocto Project Source Repositories</ulink>",
|
||
the Yocto Project maintains source repositories at
|
||
<ulink url='&YOCTO_GIT_URL;/cgit.cgi'></ulink>.
|
||
If you look at this web-interface of the repositories, each item is a separate
|
||
Git repository.
|
||
</para>
|
||
|
||
<para>
|
||
Git repositories use branching techniques that track content change (not files)
|
||
within a project (e.g. a new feature or updated documentation).
|
||
Creating a tree-like structure based on project divergence allows for excellent historical
|
||
information over the life of a project.
|
||
This methodology also allows for an environment from which you can do lots of
|
||
local experimentation on projects as you develop changes or new features.
|
||
</para>
|
||
|
||
<para>
|
||
A Git repository represents all development efforts for a given project.
|
||
For example, the Git repository <filename>poky</filename> contains all changes
|
||
and developments for Poky over the course of its entire life.
|
||
That means that all changes that make up all releases are captured.
|
||
The repository maintains a complete history of changes.
|
||
</para>
|
||
|
||
<para>
|
||
You can create a local copy of any repository by "cloning" it with the Git
|
||
<filename>clone</filename> command.
|
||
When you clone a Git repository, you end up with an identical copy of the
|
||
repository on your development system.
|
||
Once you have a local copy of a repository, you can take steps to develop locally.
|
||
For examples on how to clone Git repositories, see the
|
||
"<link linkend='getting-setup'>Getting Set Up</link>" section.
|
||
</para>
|
||
|
||
<para>
|
||
It is important to understand that Git tracks content change and
|
||
not files.
|
||
Git uses "branches" to organize different development efforts.
|
||
For example, the <filename>poky</filename> repository has
|
||
several branches that include the current
|
||
<filename>&DISTRO_NAME_NO_CAP;</filename> branch, the
|
||
<filename>master</filename> branch, and many branches for past
|
||
Yocto Project releases.
|
||
You can see all the branches by going to
|
||
<ulink url='&YOCTO_GIT_URL;/cgit.cgi/poky/'></ulink> and
|
||
clicking on the
|
||
<filename><ulink url='&YOCTO_GIT_URL;/cgit.cgi/poky/refs/heads'>[...]</ulink></filename>
|
||
link beneath the "Branch" heading.
|
||
</para>
|
||
|
||
<para>
|
||
Each of these branches represents a specific area of development.
|
||
The <filename>master</filename> branch represents the current or most recent
|
||
development.
|
||
All other branches represent offshoots of the <filename>master</filename>
|
||
branch.
|
||
</para>
|
||
|
||
<para>
|
||
When you create a local copy of a Git repository, the copy has the same set
|
||
of branches as the original.
|
||
This means you can use Git to create a local working area (also called a branch)
|
||
that tracks a specific development branch from the source Git repository.
|
||
in other words, you can define your local Git environment to work on any development
|
||
branch in the repository.
|
||
To help illustrate, here is a set of commands that creates a local copy of the
|
||
<filename>poky</filename> Git repository and then creates and checks out a local
|
||
Git branch that tracks the Yocto Project &DISTRO; Release (&DISTRO_NAME;) development:
|
||
<literallayout class='monospaced'>
|
||
$ cd ~
|
||
$ git clone git://git.yoctoproject.org/poky
|
||
$ cd poky
|
||
$ git checkout -b &DISTRO_NAME_NO_CAP; origin/&DISTRO_NAME_NO_CAP;
|
||
</literallayout>
|
||
In this example, the name of the top-level directory of your local
|
||
<ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
|
||
is "poky" and the name of that local working area (local branch)
|
||
you just created and checked out is "&DISTRO_NAME_NO_CAP;".
|
||
The files in your local repository now reflect the same files that
|
||
are in the "&DISTRO_NAME_NO_CAP;" development branch of the
|
||
Yocto Project's "poky" upstream repository.
|
||
It is important to understand that when you create and checkout a
|
||
local working branch based on a branch name,
|
||
your local environment matches the "tip" of that development branch
|
||
at the time you created your local branch, which could be
|
||
different from the files at the time of a similarly named release.
|
||
In other words, creating and checking out a local branch based on
|
||
the "&DISTRO_NAME_NO_CAP;" branch name is not the same as
|
||
cloning and checking out the "master" branch.
|
||
Keep reading to see how you create a local snapshot of a Yocto
|
||
Project Release.
|
||
</para>
|
||
|
||
<para>
|
||
Git uses "tags" to mark specific changes in a repository.
|
||
Typically, a tag is used to mark a special point such as the final
|
||
change before a project is released.
|
||
You can see the tags used with the <filename>poky</filename> Git
|
||
repository by going to
|
||
<ulink url='&YOCTO_GIT_URL;/cgit.cgi/poky/'></ulink> and
|
||
clicking on the
|
||
<filename><ulink url='&YOCTO_GIT_URL;/cgit.cgi/poky/refs/tags'>[...]</ulink></filename>
|
||
link beneath the "Tag" heading.
|
||
</para>
|
||
|
||
<para>
|
||
Some key tags are
|
||
<filename>dizzy-12.0.0</filename>,
|
||
<filename>fido-13.0.0</filename>,
|
||
<filename>jethro-14.0.0</filename>, and
|
||
<filename>&DISTRO_NAME_NO_CAP;-&POKYVERSION;</filename>.
|
||
These tags represent Yocto Project releases.
|
||
</para>
|
||
|
||
<para>
|
||
When you create a local copy of the Git repository, you also have access to all the
|
||
tags.
|
||
Similar to branches, you can create and checkout a local working Git branch based
|
||
on a tag name.
|
||
When you do this, you get a snapshot of the Git repository that reflects
|
||
the state of the files when the change was made associated with that tag.
|
||
The most common use is to checkout a working branch that matches a specific
|
||
Yocto Project release.
|
||
Here is an example:
|
||
<literallayout class='monospaced'>
|
||
$ cd ~
|
||
$ git clone git://git.yoctoproject.org/poky
|
||
$ cd poky
|
||
$ git checkout -b my-&DISTRO_NAME_NO_CAP;-&POKYVERSION; &DISTRO_NAME_NO_CAP;-&POKYVERSION;
|
||
</literallayout>
|
||
In this example, the name of the top-level directory of your local Yocto Project
|
||
Files Git repository is <filename>poky</filename>.
|
||
And, the name of the local branch you have created and checked out is
|
||
<filename>my-&DISTRO_NAME_NO_CAP;-&POKYVERSION;</filename>.
|
||
The files in your repository now exactly match the Yocto Project &DISTRO;
|
||
Release tag (<filename>&DISTRO_NAME_NO_CAP;-&POKYVERSION;</filename>).
|
||
It is important to understand that when you create and checkout a local
|
||
working branch based on a tag, your environment matches a specific point
|
||
in time and not the entire development branch.
|
||
</para>
|
||
</section>
|
||
|
||
<section id='basic-commands'>
|
||
<title>Basic Commands</title>
|
||
|
||
<para>
|
||
Git has an extensive set of commands that lets you manage changes and perform
|
||
collaboration over the life of a project.
|
||
Conveniently though, you can manage with a small set of basic operations and workflows
|
||
once you understand the basic philosophy behind Git.
|
||
You do not have to be an expert in Git to be functional.
|
||
A good place to look for instruction on a minimal set of Git commands is
|
||
<ulink url='http://git-scm.com/documentation'>here</ulink>.
|
||
If you need to download Git, you can do so
|
||
<ulink url='http://git-scm.com/download'>here</ulink>, although
|
||
any reasonably current Linux distribution should already have an
|
||
installable package for Git.
|
||
</para>
|
||
|
||
<para>
|
||
If you do not know much about Git, you should educate
|
||
yourself by visiting the links previously mentioned.
|
||
</para>
|
||
|
||
<para>
|
||
The following list briefly describes some basic Git operations as a way to get started.
|
||
As with any set of commands, this list (in most cases) simply shows the base command and
|
||
omits the many arguments they support.
|
||
See the Git documentation for complete descriptions and strategies on how to use these commands:
|
||
<itemizedlist>
|
||
<listitem><para><emphasis><filename>git init</filename>:</emphasis> Initializes an empty Git repository.
|
||
You cannot use Git commands unless you have a <filename>.git</filename> repository.</para></listitem>
|
||
<listitem><para><emphasis><filename>git clone</filename>:</emphasis>
|
||
Creates a local clone of a Git repository.
|
||
During collaboration, this command allows you to create a
|
||
local Git repository that is on equal footing with a fellow
|
||
developer’s Git repository.
|
||
</para></listitem>
|
||
<listitem><para><emphasis><filename>git add</filename>:</emphasis> Stages updated file contents
|
||
to the index that
|
||
Git uses to track changes.
|
||
You must stage all files that have changed before you can commit them.</para></listitem>
|
||
<listitem><para><emphasis><filename>git commit</filename>:</emphasis> Creates a "commit" that documents
|
||
the changes you made.
|
||
Commits are used for historical purposes, for determining if a maintainer of a project
|
||
will allow the change, and for ultimately pushing the change from your local Git repository
|
||
into the project’s upstream (or master) repository.</para></listitem>
|
||
<listitem><para><emphasis><filename>git status</filename>:</emphasis> Reports any modified files that
|
||
possibly need to be staged and committed.</para></listitem>
|
||
<listitem><para><emphasis><filename>git checkout</filename> <replaceable>branch-name</replaceable>:</emphasis> Changes
|
||
your working branch.
|
||
This command is analogous to "cd".</para></listitem>
|
||
<listitem><para><emphasis><filename>git checkout –b</filename> <replaceable>working-branch</replaceable>:</emphasis> Creates
|
||
a working branch on your local machine where you can isolate work.
|
||
It is a good idea to use local branches when adding specific features or changes.
|
||
This way if you do not like what you have done you can easily get rid of the work.</para></listitem>
|
||
<listitem><para><emphasis><filename>git branch</filename>:</emphasis> Reports
|
||
existing local branches and
|
||
tells you the branch in which you are currently working.</para></listitem>
|
||
<listitem><para><emphasis><filename>git branch -D</filename> <replaceable>branch-name</replaceable>:</emphasis>
|
||
Deletes an existing local branch.
|
||
You need to be in a local branch other than the one you are deleting
|
||
in order to delete <replaceable>branch-name</replaceable>.</para></listitem>
|
||
<listitem><para><emphasis><filename>git pull</filename>:</emphasis> Retrieves information
|
||
from an upstream Git
|
||
repository and places it in your local Git repository.
|
||
You use this command to make sure you are synchronized with the repository
|
||
from which you are basing changes (.e.g. the master branch).</para></listitem>
|
||
<listitem><para><emphasis><filename>git push</filename>:</emphasis>
|
||
Sends all your committed local changes to an upstream Git
|
||
repository (e.g. a contribution repository).
|
||
The maintainer of the project draws from these repositories
|
||
when adding changes to the project’s master repository or
|
||
other development branch.
|
||
</para></listitem>
|
||
<listitem><para><emphasis><filename>git merge</filename>:</emphasis> Combines or adds changes from one
|
||
local branch of your repository with another branch.
|
||
When you create a local Git repository, the default branch is named "master".
|
||
A typical workflow is to create a temporary branch for isolated work, make and commit your
|
||
changes, switch to your local master branch, merge the changes from the temporary branch into the
|
||
local master branch, and then delete the temporary branch.</para></listitem>
|
||
<listitem><para><emphasis><filename>git cherry-pick</filename>:</emphasis> Choose and apply specific
|
||
commits from one branch into another branch.
|
||
There are times when you might not be able to merge all the changes in one branch with
|
||
another but need to pick out certain ones.</para></listitem>
|
||
<listitem><para><emphasis><filename>gitk</filename>:</emphasis> Provides a GUI view of the branches
|
||
and changes in your local Git repository.
|
||
This command is a good way to graphically see where things have diverged in your
|
||
local repository.</para></listitem>
|
||
<listitem><para><emphasis><filename>git log</filename>:</emphasis> Reports a history of your changes to the
|
||
repository.</para></listitem>
|
||
<listitem><para><emphasis><filename>git diff</filename>:</emphasis> Displays line-by-line differences
|
||
between your local working files and the same files in the upstream Git repository that your
|
||
branch currently tracks.</para></listitem>
|
||
</itemizedlist>
|
||
</para>
|
||
</section>
|
||
</section>
|
||
|
||
<section id='workflows'>
|
||
<title>Workflows</title>
|
||
|
||
<para>
|
||
This section provides some overview on workflows using Git.
|
||
In particular, the information covers basic practices that describe roles and actions in a
|
||
collaborative development environment.
|
||
Again, if you are familiar with this type of development environment, you might want to just
|
||
skip this section.
|
||
</para>
|
||
|
||
<para>
|
||
The Yocto Project files are maintained using Git in a "master" branch whose Git history
|
||
tracks every change and whose structure provides branches for all diverging functionality.
|
||
Although there is no need to use Git, many open source projects do so.
|
||
For the Yocto Project, a key individual called the "maintainer" is responsible for the "master"
|
||
branch of a given Git repository.
|
||
The "master" branch is the “upstream” repository where the final builds of the project occur.
|
||
The maintainer is responsible for accepting changes from other developers and for
|
||
organizing the underlying branch structure to reflect release strategies and so forth.
|
||
<note>For information on finding out who is responsible for (maintains)
|
||
a particular area of code, see the
|
||
"<link linkend='how-to-submit-a-change'>How to Submit a Change</link>"
|
||
section.
|
||
</note>
|
||
</para>
|
||
|
||
<para>
|
||
The project also has an upstream contribution Git repository named
|
||
<filename>poky-contrib</filename>.
|
||
You can see all the branches in this repository using the web interface
|
||
of the
|
||
<ulink url='&YOCTO_GIT_URL;'>Source Repositories</ulink> organized
|
||
within the "Poky Support" area.
|
||
These branches temporarily hold changes to the project that have been
|
||
submitted or committed by the Yocto Project development team and by
|
||
community members who contribute to the project.
|
||
The maintainer determines if the changes are qualified to be moved
|
||
from the "contrib" branches into the "master" branch of the Git
|
||
repository.
|
||
</para>
|
||
|
||
<para>
|
||
Developers (including contributing community members) create and maintain cloned repositories
|
||
of the upstream "master" branch.
|
||
These repositories are local to their development platforms and are used to develop changes.
|
||
When a developer is satisfied with a particular feature or change, they "push" the changes
|
||
to the appropriate "contrib" repository.
|
||
</para>
|
||
|
||
<para>
|
||
Developers are responsible for keeping their local repository up-to-date with "master".
|
||
They are also responsible for straightening out any conflicts that might arise within files
|
||
that are being worked on simultaneously by more than one person.
|
||
All this work is done locally on the developer’s machines before anything is pushed to a
|
||
"contrib" area and examined at the maintainer’s level.
|
||
</para>
|
||
|
||
<para>
|
||
A somewhat formal method exists by which developers commit changes and push them into the
|
||
"contrib" area and subsequently request that the maintainer include them into "master"
|
||
This process is called “submitting a patch” or "submitting a change."
|
||
For information on submitting patches and changes, see the
|
||
"<link linkend='how-to-submit-a-change'>How to Submit a Change</link>" section.
|
||
</para>
|
||
|
||
<para>
|
||
To summarize the environment: a single point of entry exists for
|
||
changes into the project’s "master" branch of the Git repository,
|
||
which is controlled by the project’s maintainer.
|
||
And, a set of developers exist who independently develop, test, and
|
||
submit changes to "contrib" areas for the maintainer to examine.
|
||
The maintainer then chooses which changes are going to become a
|
||
permanent part of the project.
|
||
</para>
|
||
|
||
<para>
|
||
<imagedata fileref="figures/git-workflow.png" width="6in" depth="3in" align="left" scalefit="1" />
|
||
</para>
|
||
|
||
<para>
|
||
While each development environment is unique, there are some best practices or methods
|
||
that help development run smoothly.
|
||
The following list describes some of these practices.
|
||
For more information about Git workflows, see the workflow topics in the
|
||
<ulink url='http://book.git-scm.com'>Git Community Book</ulink>.
|
||
<itemizedlist>
|
||
<listitem><para><emphasis>Make Small Changes:</emphasis> It is best to keep the changes you commit
|
||
small as compared to bundling many disparate changes into a single commit.
|
||
This practice not only keeps things manageable but also allows the maintainer
|
||
to more easily include or refuse changes.</para>
|
||
<para>It is also good practice to leave the repository in a state that allows you to
|
||
still successfully build your project. In other words, do not commit half of a feature,
|
||
then add the other half as a separate, later commit.
|
||
Each commit should take you from one buildable project state to another
|
||
buildable state.</para></listitem>
|
||
<listitem><para><emphasis>Use Branches Liberally:</emphasis> It is very easy to create, use, and
|
||
delete local branches in your working Git repository.
|
||
You can name these branches anything you like.
|
||
It is helpful to give them names associated with the particular feature or change
|
||
on which you are working.
|
||
Once you are done with a feature or change and have merged it
|
||
into your local master branch, simply discard the temporary
|
||
branch.</para></listitem>
|
||
<listitem><para><emphasis>Merge Changes:</emphasis> The <filename>git merge</filename>
|
||
command allows you to take the
|
||
changes from one branch and fold them into another branch.
|
||
This process is especially helpful when more than a single developer might be working
|
||
on different parts of the same feature.
|
||
Merging changes also automatically identifies any collisions or "conflicts"
|
||
that might happen as a result of the same lines of code being altered by two different
|
||
developers.</para></listitem>
|
||
<listitem><para><emphasis>Manage Branches:</emphasis> Because branches are easy to use, you should
|
||
use a system where branches indicate varying levels of code readiness.
|
||
For example, you can have a "work" branch to develop in, a "test" branch where the code or
|
||
change is tested, a "stage" branch where changes are ready to be committed, and so forth.
|
||
As your project develops, you can merge code across the branches to reflect ever-increasing
|
||
stable states of the development.</para></listitem>
|
||
<listitem><para><emphasis>Use Push and Pull:</emphasis> The push-pull workflow is based on the
|
||
concept of developers "pushing" local commits to a remote repository, which is
|
||
usually a contribution repository.
|
||
This workflow is also based on developers "pulling" known states of the project down into their
|
||
local development repositories.
|
||
The workflow easily allows you to pull changes submitted by other developers from the
|
||
upstream repository into your work area ensuring that you have the most recent software
|
||
on which to develop.
|
||
The Yocto Project has two scripts named <filename>create-pull-request</filename> and
|
||
<filename>send-pull-request</filename> that ship with the release to facilitate this
|
||
workflow.
|
||
You can find these scripts in the <filename>scripts</filename>
|
||
folder of the
|
||
<ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
|
||
For information on how to use these scripts, see the
|
||
"<link linkend='pushing-a-change-upstream'>Using Scripts to Push a Change Upstream and Request a Pull</link>" section.
|
||
</para></listitem>
|
||
<listitem><para><emphasis>Patch Workflow:</emphasis> This workflow allows you to notify the
|
||
maintainer through an email that you have a change (or patch) you would like considered
|
||
for the "master" branch of the Git repository.
|
||
To send this type of change, you format the patch and then send the email using the Git commands
|
||
<filename>git format-patch</filename> and <filename>git send-email</filename>.
|
||
For information on how to use these scripts, see the
|
||
"<link linkend='how-to-submit-a-change'>How to Submit a Change</link>"
|
||
section.
|
||
</para></listitem>
|
||
</itemizedlist>
|
||
</para>
|
||
</section>
|
||
|
||
<section id='submitting-a-defect-against-the-yocto-project'>
|
||
<title>Submitting a Defect Against the Yocto Project</title>
|
||
|
||
<para>
|
||
Use the Yocto Project implementation of
|
||
<ulink url='http://www.bugzilla.org/about/'>Bugzilla</ulink>
|
||
to submit a defect (bug) against the Yocto Project.
|
||
For additional information on this implementation of Bugzilla see the
|
||
"<ulink url='&YOCTO_DOCS_REF_URL;#resources-bugtracker'>Yocto Project Bugzilla</ulink>"
|
||
section in the Yocto Project Reference Manual.
|
||
For more detail on any of the following steps, see the Yocto Project
|
||
<ulink url='&YOCTO_WIKI_URL;/wiki/Bugzilla_Configuration_and_Bug_Tracking'>Bugzilla wiki page</ulink>.
|
||
</para>
|
||
|
||
<para>
|
||
Use the following general steps to submit a bug"
|
||
|
||
<orderedlist>
|
||
<listitem><para>
|
||
Open the Yocto Project implementation of
|
||
<ulink url='&YOCTO_BUGZILLA_URL;'>Bugzilla</ulink>.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Click "File a Bug" to enter a new bug.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Choose the appropriate "Classification", "Product", and
|
||
"Component" for which the bug was found.
|
||
Bugs for the Yocto Project fall into one of several
|
||
classifications, which in turn break down into several
|
||
products and components.
|
||
For example, for a bug against the
|
||
<filename>meta-intel</filename> layer, you would choose
|
||
"Build System, Metadata & Runtime", "BSPs", and
|
||
"bsps-meta-intel", respectively.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Choose the "Version" of the Yocto Project for which you found
|
||
the bug (e.g. &DISTRO;).
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Determine and select the "Severity" of the bug.
|
||
The severity indicates how the bug impacted your work.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Choose the "Hardware" that the bug impacts.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Choose the "Architecture" that the bug impacts.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Choose a "Documentation change" item for the bug.
|
||
Fixing a bug might or might not affect the Yocto Project
|
||
documentation.
|
||
If you are unsure of the impact to the documentation, select
|
||
"Don't Know".
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Provide a brief "Summary" of the bug.
|
||
Try to limit your summary to just a line or two and be sure
|
||
to capture the essence of the bug.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Provide a detailed "Description" of the bug.
|
||
You should provide as much detail as you can about the context,
|
||
behavior, output, and so forth that surrounds the bug.
|
||
You can even attach supporting files for output from logs by
|
||
using the "Add an attachment" button.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Click the "Submit Bug" button submit the bug.
|
||
A new Bugzilla number is assigned to the bug and the defect
|
||
is logged in the bug tracking system.
|
||
</para></listitem>
|
||
</orderedlist>
|
||
Once you file a bug, the bug is processed by the Yocto Project Bug
|
||
Triage Team and further details concerning the bug are assigned
|
||
(e.g. priority and owner).
|
||
You are the "Submitter" of the bug and any further categorization,
|
||
progress, or comments on the bug result in Bugzilla sending you an
|
||
automated email concerning the particular change or progress to the
|
||
bug.
|
||
</para>
|
||
</section>
|
||
|
||
<section id='how-to-submit-a-change'>
|
||
<title>How to Submit a Change</title>
|
||
|
||
<para>
|
||
Contributions to the Yocto Project and OpenEmbedded are very welcome.
|
||
Because the system is extremely configurable and flexible, we recognize that developers
|
||
will want to extend, configure or optimize it for their specific uses.
|
||
You should send patches to the appropriate mailing list so that they
|
||
can be reviewed and merged by the appropriate maintainer.
|
||
</para>
|
||
|
||
<section id='submit-change-overview'>
|
||
<title>Overview</title>
|
||
|
||
<para>
|
||
The Yocto Project uses a mailing list and patch-based workflow
|
||
that is similar to the Linux kernel but contains important
|
||
differences.
|
||
In general, a mailing list exists through which you can submit
|
||
patches.
|
||
The specific mailing list you need to use depends on the
|
||
location of the code you are changing.
|
||
Each component (e.g. layer) should have a
|
||
<filename>README</filename> file that indicates where to send
|
||
the changes and which process to follow.
|
||
</para>
|
||
|
||
<para>
|
||
You can send the patch to the mailing list using whichever approach
|
||
you feel comfortable with to generate the patch.
|
||
Once sent, the patch is usually reviewed by the community at large.
|
||
If somebody has concerns with the patch, they will usually voice
|
||
their concern over the mailing list.
|
||
If a patch does not receive any negative reviews, the maintainer of
|
||
the affected layer typically takes the patch, tests it, and then
|
||
based on successful testing, merges the patch.
|
||
</para>
|
||
|
||
<para>
|
||
Specific to OpenEmbedded-Core, two commonly used testing trees
|
||
exist:
|
||
<itemizedlist>
|
||
<listitem><para>
|
||
<emphasis>"ross/mut" branch:</emphasis>
|
||
The "mut" (master-under-test) tree
|
||
exists in the <filename>poky-contrib</filename> repository
|
||
in the
|
||
<ulink url='&YOCTO_GIT_URL;'>Yocto Project source repositories</ulink>.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
<emphasis>"master-next" branch:</emphasis>
|
||
This branch is part of the main
|
||
"poky" repository in the Yocto Project source repositories.
|
||
</para></listitem>
|
||
</itemizedlist>
|
||
Maintainers use these branches to test submissions prior to merging
|
||
patches.
|
||
Thus, you can get an idea of the status of a patch based on
|
||
whether the patch has been merged into one of these branches.
|
||
</para>
|
||
|
||
<para>
|
||
This system is imperfect and patches can sometimes get lost in the
|
||
flow.
|
||
Asking about the status of a patch is reasonable if the patch
|
||
has been idle for a while with no feedback.
|
||
The Yocto Project does have plans to use
|
||
<ulink url='https://en.wikipedia.org/wiki/Patchwork_(software)'>Patchwork</ulink>
|
||
to track the status of patches and also to automatically preview
|
||
patches.
|
||
</para>
|
||
|
||
<para>
|
||
The following sections provide general instructions for both
|
||
pushing changes upstream and for submitting changes as patches.
|
||
</para>
|
||
</section>
|
||
|
||
<section id='submit-change-submissions-to-poky'>
|
||
<title>Submissions to Poky</title>
|
||
|
||
<para>
|
||
The "poky" repository, which is the Yocto Project's reference build
|
||
environment, is a hybrid repository that contains several
|
||
individual pieces (e.g. BitBake, OpenEmbedded-Core, meta-yocto,
|
||
documentation, and so forth) built using the combo-layer tool.
|
||
The upstream location used for submitting changes varies by
|
||
component:
|
||
<itemizedlist>
|
||
<listitem><para>
|
||
<emphasis>Core Metadata:</emphasis>
|
||
Send your patch to the
|
||
<ulink url='http://lists.openembedded.org/mailman/listinfo/openembedded-core'>openembedded-core</ulink>
|
||
mailing list. For example, a change to anything under
|
||
the <filename>meta</filename> or
|
||
<filename>scripts</filename> directories should be sent
|
||
to this mailing list.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
<emphasis>BitBake:</emphasis>
|
||
For changes to BitBake (i.e. anything under the
|
||
<filename>bitbake</filename> directory), send your patch
|
||
to the
|
||
<ulink url='http://lists.openembedded.org/mailman/listinfo/bitbake-devel'>bitbake-devel</ulink>
|
||
mailing list.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
<emphasis>"meta-yocto-bsp" and "meta-poky" trees:</emphasis>
|
||
These trees are
|
||
part of the "meta-yocto" repository in the Yocto Project
|
||
source repositories.
|
||
Use the
|
||
<ulink url='https://lists.yoctoproject.org/listinfo/poky'>poky</ulink>
|
||
mailing list.
|
||
</para></listitem>
|
||
</itemizedlist>
|
||
</para>
|
||
</section>
|
||
|
||
<section id='submit-change-submissions-to-other-layers'>
|
||
<title>Submissions to Other Layers</title>
|
||
|
||
<para>
|
||
For changes to other layers hosted in the Yocto Project source
|
||
repositories (i.e. <filename>yoctoproject.org</filename>), tools,
|
||
and the Yocto Project documentation, use the
|
||
<ulink url='https://lists.yoctoproject.org/listinfo/yocto'>Yocto Project</ulink>
|
||
general mailing list.
|
||
<note>
|
||
Sometimes a layer's documentation specifies to use a
|
||
particular mailing list.
|
||
If so, use that list.
|
||
</note>
|
||
For additional recipes that do not fit into the core Metadata, you
|
||
should determine which layer the recipe should go into and submit
|
||
the change in the manner recommended by the documentation (e.g.
|
||
the <filename>README</filename> file) supplied with the layer.
|
||
If in doubt, please ask on the Yocto general mailing list or on
|
||
the openembedded-devel mailing list.
|
||
</para>
|
||
</section>
|
||
|
||
<section id='submit-change-patch-submission-details'>
|
||
<title>Patch Submission Details</title>
|
||
|
||
<para>
|
||
When submitting any change, you can check who you should be
|
||
notifying.
|
||
Use either of these methods to find out:
|
||
<itemizedlist>
|
||
<listitem><para>
|
||
<emphasis>Maintenance File:</emphasis>
|
||
Examine the <filename>maintainers.inc</filename> file, which is
|
||
located in the
|
||
<ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
|
||
at <filename>meta-poky/conf/distro/include</filename>, to
|
||
see who is responsible for code.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
<emphasis>Search by File:</emphasis>
|
||
Using <link linkend='git'>Git</link>, you can enter the
|
||
following command to bring up a short list of all commits
|
||
against a specific file:
|
||
<literallayout class='monospaced'>
|
||
git shortlog -- <replaceable>filename</replaceable>
|
||
</literallayout>
|
||
Just provide the name of the file for which you are interested.
|
||
The information returned is not ordered by history but does
|
||
include a list of everyone who has committed grouped by
|
||
name.
|
||
From the list, you can see who is responsible for the bulk of
|
||
the changes against the file.
|
||
</para></listitem>
|
||
</itemizedlist>
|
||
</para>
|
||
|
||
<para>
|
||
For a list of the Yocto Project and related mailing lists, see the
|
||
"<ulink url='&YOCTO_DOCS_REF_URL;#resources-mailinglist'>Mailing lists</ulink>"
|
||
section in the Yocto Project Reference Manual.
|
||
</para>
|
||
|
||
<para>
|
||
When you send a patch, be sure to include a "Signed-off-by:"
|
||
line in the same style as required by the Linux kernel.
|
||
Adding this line signifies that you, the submitter, have agreed
|
||
to the Developer's Certificate of Origin 1.1 as follows:
|
||
<literallayout class='monospaced'>
|
||
Developer's Certificate of Origin 1.1
|
||
|
||
By making a contribution to this project, I certify that:
|
||
|
||
(a) The contribution was created in whole or in part by me and I
|
||
have the right to submit it under the open source license
|
||
indicated in the file; or
|
||
|
||
(b) The contribution is based upon previous work that, to the best
|
||
of my knowledge, is covered under an appropriate open source
|
||
license and I have the right under that license to submit that
|
||
work with modifications, whether created in whole or in part
|
||
by me, under the same open source license (unless I am
|
||
permitted to submit under a different license), as indicated
|
||
in the file; or
|
||
|
||
(c) The contribution was provided directly to me by some other
|
||
person who certified (a), (b) or (c) and I have not modified
|
||
it.
|
||
|
||
(d) I understand and agree that this project and the contribution
|
||
are public and that a record of the contribution (including all
|
||
personal information I submit with it, including my sign-off) is
|
||
maintained indefinitely and may be redistributed consistent with
|
||
this project or the open source license(s) involved.
|
||
</literallayout>
|
||
</para>
|
||
|
||
<para>
|
||
In a collaborative environment, it is necessary to have some sort
|
||
of standard or method through which you submit changes.
|
||
Otherwise, things could get quite chaotic.
|
||
One general practice to follow is to make small, controlled changes.
|
||
Keeping changes small and isolated aids review, makes
|
||
merging/rebasing easier and keeps the change history clean should
|
||
anyone need to refer to it in future.
|
||
</para>
|
||
|
||
<para>
|
||
When you make a commit, you must follow certain standards
|
||
established by the OpenEmbedded and Yocto Project development teams.
|
||
For each commit, you must provide a single-line summary of the
|
||
change and you should almost always provide a more detailed
|
||
description of what you did (i.e. the body of the commit message).
|
||
The only exceptions for not providing a detailed description would
|
||
be if your change is a simple, self-explanatory change that needs
|
||
no further description beyond the summary.
|
||
Here are the guidelines for composing a commit message:
|
||
<itemizedlist>
|
||
<listitem><para>
|
||
Provide a single-line, short summary of the change.
|
||
This summary is typically viewable in the "shortlist" of
|
||
changes.
|
||
Thus, providing something short and descriptive that
|
||
gives the reader a summary of the change is useful when
|
||
viewing a list of many commits.
|
||
You should prefix this short description with the recipe
|
||
name (if changing a recipe), or else with the short form
|
||
path to the file being changed.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
For the body of the commit message, provide detailed
|
||
information that describes what you changed, why you made
|
||
the change, and the approach you used.
|
||
It might also be helpful if you mention how you tested
|
||
the change.
|
||
Provide as much detail as you can in the body of the
|
||
commit message.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
If the change addresses a specific bug or issue that is
|
||
associated with a bug-tracking ID, include a reference
|
||
to that ID in your detailed description.
|
||
For example, the Yocto Project uses a specific convention
|
||
for bug references - any commit that addresses a specific
|
||
bug should use the following form for the detailed
|
||
description:
|
||
<literallayout class='monospaced'>
|
||
Fixes [YOCTO #<replaceable>bug-id</replaceable>]
|
||
|
||
<replaceable>detailed description of change</replaceable>
|
||
</literallayout>
|
||
</para></listitem>
|
||
Where <replaceable>bug-id</replaceable> is replaced with the
|
||
specific bug ID from the Yocto Project Bugzilla instance.
|
||
</itemizedlist>
|
||
</para>
|
||
|
||
<para>
|
||
You can find more guidance on creating well-formed commit messages
|
||
at this OpenEmbedded wiki page:
|
||
<ulink url='&OE_HOME_URL;/wiki/Commit_Patch_Message_Guidelines'></ulink>.
|
||
</para>
|
||
</section>
|
||
|
||
<section id='pushing-a-change-upstream'>
|
||
<title>Using Scripts to Push a Change Upstream and Request a Pull</title>
|
||
|
||
<para>
|
||
The basic flow for pushing a change to an upstream "contrib" Git repository is as follows:
|
||
<itemizedlist>
|
||
<listitem><para>Make your changes in your local Git repository.</para></listitem>
|
||
<listitem><para>Stage your changes by using the <filename>git add</filename>
|
||
command on each file you changed.</para></listitem>
|
||
<listitem><para>
|
||
Commit the change by using the
|
||
<filename>git commit</filename> command.
|
||
Be sure to provide a commit message that follows the
|
||
project’s commit message standards as described earlier.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Push the change to the upstream "contrib" repository by
|
||
using the <filename>git push</filename> command.
|
||
</para></listitem>
|
||
<listitem><para>Notify the maintainer that you have pushed a change by making a pull
|
||
request.
|
||
The Yocto Project provides two scripts that conveniently let you generate and send
|
||
pull requests to the Yocto Project.
|
||
These scripts are <filename>create-pull-request</filename> and
|
||
<filename>send-pull-request</filename>.
|
||
You can find these scripts in the <filename>scripts</filename> directory
|
||
within the <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.</para>
|
||
<para>Using these scripts correctly formats the requests without introducing any
|
||
whitespace or HTML formatting.
|
||
The maintainer that receives your patches needs to be able to save and apply them
|
||
directly from your emails.
|
||
Using these scripts is the preferred method for sending patches.</para>
|
||
<para>For help on using these scripts, simply provide the
|
||
<filename>-h</filename> argument as follows:
|
||
<literallayout class='monospaced'>
|
||
$ poky/scripts/create-pull-request -h
|
||
$ poky/scripts/send-pull-request -h
|
||
</literallayout></para></listitem>
|
||
</itemizedlist>
|
||
</para>
|
||
|
||
<para>
|
||
You can find general Git information on how to push a change upstream in the
|
||
<ulink url='http://git-scm.com/book/en/v2/Distributed-Git-Distributed-Workflows'>Git Community Book</ulink>.
|
||
</para>
|
||
</section>
|
||
|
||
<section id='submitting-a-patch'>
|
||
<title>Using Email to Submit a Patch</title>
|
||
|
||
<para>
|
||
You can submit patches without using the <filename>create-pull-request</filename> and
|
||
<filename>send-pull-request</filename> scripts described in the previous section.
|
||
However, keep in mind, the preferred method is to use the scripts.
|
||
</para>
|
||
|
||
<para>
|
||
Depending on the components changed, you need to submit the email
|
||
to a specific mailing list.
|
||
For some guidance on which mailing list to use, see the list in the
|
||
"<link linkend='how-to-submit-a-change'>How to Submit a Change</link>"
|
||
section.
|
||
For a description of the available mailing lists, see the
|
||
"<ulink url='&YOCTO_DOCS_REF_URL;#resources-mailinglist'>Mailing Lists</ulink>"
|
||
section in the Yocto Project Reference Manual.
|
||
</para>
|
||
|
||
<para>
|
||
Here is the general procedure on how to submit a patch through email without using the
|
||
scripts:
|
||
<orderedlist>
|
||
<listitem><para>
|
||
Make your changes in your local Git repository.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Stage your changes by using the
|
||
<filename>git add</filename> command on each file you
|
||
changed.
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Commit the change by using the
|
||
<filename>git commit --signoff</filename> command.
|
||
Using the <filename>--signoff</filename> option identifies
|
||
you as the person making the change and also satisfies
|
||
the Developer's Certificate of Origin (DCO) shown earlier.
|
||
</para>
|
||
<para>When you form a commit, you must follow certain
|
||
standards established by the Yocto Project development
|
||
team.
|
||
See the earlier section
|
||
"<link linkend='how-to-submit-a-change'>How to Submit a Change</link>"
|
||
for Yocto Project commit message standards.
|
||
</para></listitem>
|
||
<listitem><para>Format the commit into an email message.
|
||
To format commits, use the
|
||
<filename>git format-patch</filename> command.
|
||
When you provide the command, you must include a revision
|
||
list or a number of patches as part of the command.
|
||
For example, either of these two commands takes your most
|
||
recent single commit and formats it as an email message in
|
||
the current directory:
|
||
<literallayout class='monospaced'>
|
||
$ git format-patch -1
|
||
</literallayout>
|
||
or
|
||
<literallayout class='monospaced'>
|
||
$ git format-patch HEAD~
|
||
</literallayout></para>
|
||
<para>After the command is run, the current directory
|
||
contains a numbered <filename>.patch</filename> file for
|
||
the commit.</para>
|
||
<para>If you provide several commits as part of the
|
||
command, the <filename>git format-patch</filename> command
|
||
produces a series of numbered files in the current
|
||
directory – one for each commit.
|
||
If you have more than one patch, you should also use the
|
||
<filename>--cover</filename> option with the command,
|
||
which generates a cover letter as the first "patch" in
|
||
the series.
|
||
You can then edit the cover letter to provide a
|
||
description for the series of patches.
|
||
For information on the
|
||
<filename>git format-patch</filename> command,
|
||
see <filename>GIT_FORMAT_PATCH(1)</filename> displayed
|
||
using the <filename>man git-format-patch</filename>
|
||
command.
|
||
<note>
|
||
If you are or will be a frequent contributor to the
|
||
Yocto Project or to OpenEmbedded, you might consider
|
||
requesting a contrib area and the necessary associated
|
||
rights.
|
||
</note>
|
||
</para></listitem>
|
||
<listitem><para>
|
||
Import the files into your mail client by using the
|
||
<filename>git send-email</filename> command.
|
||
<note>
|
||
In order to use <filename>git send-email</filename>,
|
||
you must have the proper Git packages installed on
|
||
your host.
|
||
For Ubuntu, Debian, and Fedora the package is
|
||
<filename>git-email</filename>.
|
||
</note></para>
|
||
<para>The <filename>git send-email</filename> command
|
||
sends email by using a local or remote Mail Transport Agent
|
||
(MTA) such as <filename>msmtp</filename>,
|
||
<filename>sendmail</filename>, or through a direct
|
||
<filename>smtp</filename> configuration in your Git
|
||
<filename>~/.gitconfig</filename> file.
|
||
If you are submitting patches through email only, it is
|
||
very important that you submit them without any whitespace
|
||
or HTML formatting that either you or your mailer
|
||
introduces.
|
||
The maintainer that receives your patches needs to be able
|
||
to save and apply them directly from your emails.
|
||
A good way to verify that what you are sending will be
|
||
applicable by the maintainer is to do a dry run and send
|
||
them to yourself and then save and apply them as the
|
||
maintainer would.</para>
|
||
<para>The <filename>git send-email</filename> command is
|
||
the preferred method for sending your patches since there
|
||
is no risk of compromising whitespace in the body of the
|
||
message, which can occur when you use your own mail client.
|
||
The command also has several options that let you
|
||
specify recipients and perform further editing of the
|
||
email message.
|
||
For information on how to use the
|
||
<filename>git send-email</filename> command,
|
||
see <filename>GIT-SEND-EMAIL(1)</filename> displayed using
|
||
the <filename>man git-send-email</filename> command.
|
||
</para></listitem>
|
||
</orderedlist>
|
||
</para>
|
||
</section>
|
||
</section>
|
||
</chapter>
|
||
<!--
|
||
vim: expandtab tw=80 ts=4
|
||
-->
|